1. Technical Field
The present invention relates to projection display devices and methods for controlling a projection display device.
2. Related Art
Some projection display devices (projectors) have a protect function implemented by means of password authentication. As such a protect function, there is a protect function of locking an input when the user performs the inputting of a password unsuccessfully three times in a row and requiring the user to turn on the device and do the process again, and, when the user forgets the password, requiring the user to acquire an unlock code which is provided when the user makes contact with a support center and is confirmed to be a customer and allowing the user to unlock the password by using the unlock code. Moreover, when the user performs the inputting of a password unsuccessfully many times in a row, the protect function maintains a complete locked state in which the user cannot use the device at all unless the user takes a predetermined procedure.
Furthermore, as a protect function which is not limited to the projection display device, there is a protect function of determining whether or not an input is a simple inputting error when the contents of the input do not match a keyword and regarding the input as a correct input when determining that it is a simple error (see, for example, JP-A-5-119896). Moreover, there is a protect function of prohibiting the inputting of a password when the user unsuccessfully performs the inputting of a password continuously and allowing the user to input a password again after a lapse of a set time (see, for example, JP-A-2002-229608).
However, in an existing configuration in which the user cannot use the device when password authentication is unsuccessfully performed, it takes a good amount of time for even an authorized user to become able to use the projection display device. This causes inconvenience to the authorized user.
On the other hand, in a configuration in which, when it is determined that an input is a simple error, the input is regarded as a correct input, when a combination of numerals that are input from a remote controller is used as a password as in the projection display device, it is difficult to determine whether or not an input is a simple inputting error, and, even when the device is being stolen, there is a possibility that an unauthorized third party can use the device. This decreases security level.
Moreover, in a configuration in which the inputting of a password is permitted every time after a lapse of a set time, even an authorized user cannot use the device as long as the user continues to input an incorrect password, and there is a danger that, if the device is being stolen, a third party may become able to use the device when the third party finds the password in the course of time.